This invention relates to backpacks, and, more particularly, to a lightweight yet strong, anatomically shaped frame, a sack which is slidably attached to the frame, and a compression molded suspension system.
Backpacks are used by hikers, mountain climbers, campers, etc. for carrying camping gear, clothing, food, and the like. Backpacks fall into two broad categories--external frame backpacks and internal frame backpacks. An external frame backpack includes a frame and a separate sack which is removably mounted on the frame. An internal frame backpack includes a sack with frame structure which is integrated into the inside of the sack.
The sack of an external frame backpack is commonly attached to the frame by steel pins which are inserted through the frame and into grommets which are attached to the sack. When the sack is filled, the weight of the contents applies forces at the grommets which are point stresses. The areas of the sack where the grommets are attached therefore require costly reinforcement construction.
Weight and strength are important characteristics of a backpack frame. The frame should be light yet strong. The frame should also be shaped to fit the anatomy of the backpacker. Some frames are constructed so rigidly that the frames have little or no torsional flexibility which permits the frame to flex with movements of the body.
The suspension system of a backpack commonly includes a pair of shoulder straps, a waist belt, and a back pad. The suspension system should be adjustable to accommodate various torso shapes and should comfortably support the load on the backpacker.